What the equivalent distance between -13 and -4

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

Two poles, ab and ed, are fixed to the ground with the of ropes ac and ec, as shown: what is the approximate distance, in feet, between the two poles? 6.93 feet 8.66 feet 12.32 feet 15.59 feet